There *is* a problem with using __getattr__ though - any attribute in the chained namespaces that is shadowed by a class attribute (like 'update') will be picked up from the class, not from the chained namespaces. So we do need to use __getattribute__ to change that lookup order. However, given the amount of grief the default lookup behaviour causes, I think the place to do that is in Namespace itself:
class Namespace(object): # otherwise unchanged def __getattribute__(self, name): """Namespaces do NOT default to looking in their class dict for non-magic attributes """ getattribute = super(Namespace, self).__getattribute__ try: return getattribute("__dict__")[name] except KeyError: if name.startswith('__') and name.endswith('__'): # Employ the default lookup system for magic names return getattribute(name) else: # Skip the default lookup system for normal names if hasattr(self, "__getattr__"): return getattribute("__getattr__")(name) else: raise AttributeError(name)
Hmmm... This does seem sensible. And sidesteps the issue about suggesting that subclasses use Namespace.update instead of namespaceinstance.update -- the latter just won't work! (This is a Good Thing, IMHO.)
Anyway, it is probably worth digging into the descriptor machinery a bit further in order to design a lookup scheme that is most appropriate for namespaces, but the above example has convinced me that object.__getattribute__ is NOT it :)
Yeah, I'm going to look into this a bit more too, but let me know if you have any more insights in this area.
Steve -- http://mail.python.org/mailman/listinfo/python-list
